I am facing a problem with Java XML validation API. When an array of XSDs (schema files) is passed to method javax.xml.validation.SchemaFactory.newSchema(Source[] schemas), it throws the following exception:
org.xml.sax.SAXParseException; src-resolve: Cannot resolve the name 'Report' to a(n) 'type definition' component.
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:198)
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.error(ErrorHandlerWrapper.java:134)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:396)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:306)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDHandler.reportSchemaErr(XSDHandler.java:4162)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDHandler.reportSchemaError(XSDHandler.java:4141)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDHandler.getGlobalDecl(XSDHandler.java:1674)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDElementTraverser.traverseNamedElement(XSDElementTraverser.java:405)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDElementTraverser.traverseGlobal(XSDElementTraverser.java:242)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDHandler.traverseSchemas(XSDHandler.java:1429)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDHandler.parseSchema(XSDHandler.java:626)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaLoader.loadSchema(XMLSchemaLoader.java:613)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaLoader.loadGrammar(XMLSchemaLoader.java:572)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaLoader.loadGrammar(XMLSchemaLoader.java:538)
at com.sun.org.apache.xerces.internal.jaxp.validation.XMLSchemaFactory.newSchema(XMLSchemaFactory.java:252)
...
Below is shown part of the code used to generate the schema.
public static Object converToObject(byte[] xmlByteBuffer, int offset, int length, Class<?>... type) throws JAXBException {
JAXBContext context = JAXBContext.newInstance(type);
final List<DOMResult> results = new ArrayList<DOMResult>();
try {
context.generateSchema(new SchemaOutputResolver() {
@Override
public Result createOutput(String namespaceUri, String suggestedFileName) throws IOException {
DOMResult result = new DOMResult();
result.setSystemId(suggestedFileName);
results.add(result);
return result;
}
});
} catch (IOException e1) {
e1.printStackTrace();
}
final SchemaFactory schemaFactory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
DOMSource[] sources = new DOMSource[results.size()];
for (int i = 0; i < results.size(); i++) {
DOMResult result = results.get(i);
Node node = result.getNode();
sources[i] = new DOMSource(node);
}
// First Solution: Reverse Order
// DOMSource[] resortedSources = new DOMSource[results.size()];
// for(int i=1; i<results.size(); i++){
// sourcesSorted[results.size()-(i+1)] = sources[i];
// }
// Second Solution: Look for the XSD with imports with namespace
// attribute
for (int i = 0; i < results.size(); i++) {
Node node = sources[i].getNode();
if(thereIsElementImportWithAttributeNamespace(node)) {
DOMSource sourceBackup = sources[0];
sources[0] = sources[i];
sources[i] = sourceBackup;
break;
}
}
Schema schema = null;
try {
schema = schemaFactory.newSchema(sources);
// schema = schemaFactory.newSchema(resortedSources);
} catch (SAXException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Unmarshaller unmarshaller = context.createUnmarshaller();
unmarshaller.setSchema(schema);
unmarshaller.setEventHandler(new javax.xml.bind.helpers.DefaultValidationEventHandler());
String str;
try {
str = new String(xmlByteBuffer, offset, length, "UTF-8");
} catch (UnsupportedEncodingException uee) {
try {
str = new String(xmlByteBuffer, "ISO-8859-1");
} catch (UnsupportedEncodingException ex) {
throw new JAXBException(ex);
}
}
StreamSource ss = new StreamSource(new StringReader(str));
Object obj = unmarshaller.unmarshal(ss);
return obj;
}
Below are shown printed parts of true XSDs which are passed to method newSchema.
schema1.xsd:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://service.mw.uw/" version="1.0">
<xs:import schemaLocation="schema4.xsd"/>
<xs:element name="Report" type="Report"/>
...
</xs:schema>
schema2.xsd:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://service.gather.mw.uw/" version="1.0">
<xs:import schemaLocation="schema4.xsd"/>
<xs:element name="DataReport" type="DataReport"/>
...
</xs:schema>
schema3.xsd:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:tns="http://service.commons.uw/" targetNamespace="http://service.commons.uw/" version="1.0">
<xs:import schemaLocation="schema4.xsd"/>
<xs:element name="ApplicationRequest" type="ApplicationRequest"/>
...
</xs:schema>
schema4.xsd:
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:ns1="http://service.commons.uw/" xmlns:ns2="http://service.gather.mw.uw/" version="1.0">
<xs:import namespace="http://service.commons.uw/" schemaLocation="schema3.xsd"/>
<xs:import namespace="http://service.gather.mw.uw/" schemaLocation="schema2.xsd"/>
<xs:complexType name="message">
...
</xs:complexType>
...
</xs:schema>
It is spread abroad that SchemaFactory.newSchema cannot deal with multiple XSDs importing multiple XSDs.
According to Hedleys, a solution would be to sort any array of XSDs with imported XSDs before the ones which actually import them. I faced a problem with this solution, because in my project there are several mutual imports among XSDs. So how could that be sorted?
Also, according to jtahlborn, another solution is to resort XSD arrays in opposite order. That worked fine! However, I kept researching the problem because, in the time, I had just few different cases to test if that solution was generic enough!
The Java Documentation of the method SchemaFactory.newSchema states the following: "Section 4.2.3 of the XML Schema recommendation describes the options processors have in this regard. While a processor should be consistent in its treatment of JAXP schema sources and XML Schema imports, the behaviour between JAXP-compliant parsers may vary; in particular, parsers may choose to ignore all but the first for a given namespace, regardless of information provided in schemaLocation". So based on that statement, I could fix the exception mentioned early, by placing the XSD with imports containing namespace attribute in the first position of the XSD array. So finally, here comes my question:
Is the cause of the exception, the lack of namespace attribute in the imports of the first XSD read from the array of XSDs?
I could only test that last solution with few different cases, but all worked just fine! If someone has more test cases to try, please let we know if that last solution really works in any case.
